Yeah, it so fast that AMD is not even able to catchup and that many of the extensions is available only on Intel CPUs.
As far as I could tell, it is only unstable in the sense of being fast and having many features. I dont see any breaking for my code using cpuid to detect avx512 features.
No, I mean things like when they removed BCD support, or when they removed simultaneous 16-bit ISA when they added 64-bit. Or the bit string instructions. Or moving the cmpxchg encoding across chip revisions.
As far as I could tell, it is only unstable in the sense of being fast and having many features. I dont see any breaking for my code using cpuid to detect avx512 features.